Sorry, those aren’t customizable in CT as far as I know. I think they’re more of a system-level thing.
Do you have them via Fn+<key> though? Some laptops use Fn + arrow keys for them (up/down for PgUp/Pgdn, and left/right for Home/End). You might try those even if they’re not marked. Or look up your model online and see if you can find the info on how to do them.